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‣ Seleção de habitat e natureza polimórfica em populações do camarão Hippolyte obliquimanus Dana, 1852 (Decapoda; Caridea); Habitat selection and polymorphic nature in populations of the shrimp Hippolyte obliquimanus Dana, 1852 (Decapoda: Caridea)

Duarte, Rafael Campos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 05/10/2011 Português
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O polimorfismo cromático é bastante comum em diversos grupos animais, podendo ser determinado geneticamente ou induzido por pistas ambientais. A existência de padrões de cor distintos em uma espécie pode variar de acordo com o tamanho e o sexo dos indivíduos na população. Além disso, os mesmos podem se diferenciar em suas características morfológicas e reprodutivas, as quais, por sua vez, estão associadas a aspectos comportamentais, ecológicos ou fisiológicos distintos. Dessa forma, diferentes estratégias de vida, caracterizadas por custos/benefícios específicos, podem ser selecionadas para cada padrão de cor. O camarão carídeo Hippolyte obliquimanus é um membro importante da fauna de águas costeiras tropicais, vivendo em associação com bancos de algas. Apresenta dois padrões de cor distintos: o primeiro é formado por animais com coloração homogênea marrom-esverdeada (M-E), rosa (R) ou preta (P); e o segundo por animais de coloração disruptiva (D), caracterizados por indivíduos com uma listra longitudinal transparente no abdômen ou por bandas circulares coloridas ao longo do corpo. O presente trabalho teve como principal objetivo avaliar possíveis mecanismos reguladores da condição polimórfica em H. obliquimanus. Para isso...

‣ Environmental cues during overland dispersal by three freshwater invaders: Eriocheir sinensis, Pacifastacus leniusculus, and Procambarus clarkii (Crustacea, Decapoda)

Marques, M.; Banha, F.; Águas, M.; Anastácio, P.
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Artigo de Revista Científica
Português
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Freshwater crustaceans are known to disperse overland, aiding the invasion of new environments. To analyze the effect of environmental variables (humidity, temperature, illuminance, vegetation, and slope) on the movement direction of Eriocheir sinensis (H. Milne Edwards, 1853), Pacifastacus leniusculus (Dana, 1852) and Procambarus clarkii (Girard, 1852) in land, the animals were placed at the centre of a metal gutter and given a choice between two values of each variable. Chi-squared tests revealed significant preferences for E. sinensis to move downhill, P. leniusculus to move toward cooler areas and P. clarkii to move downhill and toward cooler areas. To test the ability of P. leniusculus and P. clarkii (E. sinensis was not present at the testing site) to return to water, they were placed in a circular arena near the river bank and their direction of movement was recorded. Chi-squared tests revealed that P. leniusculus, when isolated and in groups of 6, showed a significant tendency to move downstream, but not directly toward the water. P. clarkii showed no significant preference in movement direction. Since movement direction and overland dispersal are influenced by environmental gradients of temperature and elevation, these variables are fundamental for predicting autonomous overland dispersal and colonization patterns.

‣ Factors inducing overland movement of invasive crayfish (Procambarus clarkii) in a ricefield habitat

Ramalho, Ricardo Oliveira; Anastácio, Pedro Manuel
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Artigo de Revista Científica
Português
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Freshwater crustaceans are known to disperse overland, aiding the invasion of new environments. To analyze the effect of environmental variables (humidity, temperature, illuminance, vegetation, and slope) on the movement direction of Eriocheir sinensis (H. Milne Edwards, 1853), Pacifastacus leniusculus (Dana, 1852) and Procambarus clarkii (Girard, 1852) in land, the animals were placed at the centre of a metal gutter and given a choice between two values of each variable. Chi-squared tests revealed significant preferences for E. sinensis to move downhill, P. leniusculus to move toward cooler areas and P. clarkii to move downhill and toward cooler areas. To test the ability of P. leniusculus and P. clarkii (E. sinensis was not present at the testing site) to return to water, they were placed in a circular arena near the river bank and their direction of movement was recorded. Chi-squared tests revealed that P. leniusculus, when isolated and in groups of 6, showed a significant tendency to move downstream, but not directly toward the water. P. clarkii showed no significant preference in movement direction. Since movement direction and overland dispersal are influenced by environmental gradients of temperature and elevation, these variables are fundamental for predicting autonomous overland dispersal and colonization patterns.

‣ Copepod distribution and production in a Mid-Atlantic Ridge archipelago

MELO,PEDRO A.M.C.; MELO JÚNIOR,MAURO DE; MACÊDO,SILVIO J. DE; ARAUJO,MOACYR; NEUMANN-LEITÃO,SIGRID
Fonte: Academia Brasileira de Ciências Publicador: Academia Brasileira de Ciências
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 Português
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The Saint Peter and Saint Paul Archipelago (SPSPA) are located close to the Equator in the Atlantic Ocean. The aim of this study was to assess the spatial variations in the copepod community abundance, and the biomass and production patterns of the three most abundant calanoid species in the SPSPA. Plankton samples were collected with a 300 µm mesh size net along four transects (north, east, south and west of the SPSPA), with four stations plotted in each transect. All transects exhibited a tendency toward a decrease in copepod density with increasing distance from the SPSPA, statistically proved in the North. Density varied from 3.33 to 182.18 ind.m−3, and differences were also found between the first perimeter (first circular distance band) and the others. The total biomass varied from 15.25 to 524.50 10−3 mg C m−3 and production from 1.19 to 22.04 10−3 mg C m−3d−1. The biomass and production of Undinula vulgaris (Dana, 1849), Acrocalanus longicornis Giesbrecht, 1888 and Calocalanus pavo (Dana, 1849) showed differences between some transects. A trend of declining biodiversity and production with increasing distance from archipelago was observed, suggesting that even small features like the SPSPA can affect the copepod community in tropical oligotrophic oceanic areas.

‣ Patches of synchronized activity in the cerebellar cortex evoked by mossy-fiber stimulation: Questioning the role of parallel fibers

Cohen, Dana; Yarom, Yosef
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 08/12/1998 Português
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The discrepancy between the structural longitudinal organization of the parallel-fiber system in the cerebellar cortex and the functional mosaic-like organization of the cortex has provoked controversial theories about the flow of information in the cerebellum. We address this issue by characterizing the spatiotemporal organization of neuronal activity in the cerebellar cortex by using optical imaging of voltage-sensitive dyes in isolated guinea-pig cerebellum. Parallel-fiber stimulation evoked a narrow beam of activity, which propagated along the parallel fibers. Stimulation of the mossy fibers elicited a circular, nonpropagating patch of synchronized activity. These results strongly support the hypothesis that a beam of parallel fibers, activated by a focal group of granule cells, fails to activate the Purkinje cells along most of its length. It is thus the ascending axon of the granule cell, and not its parallel branches, that activates and defines the basic functional modules of the cerebellar cortex.

‣ Multicopy Plasmid Modification with Phage λ Red Recombineering

Thomason, Lynn C.; Costantino, Nina; Shaw, Dana V.; Court, Donald L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
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Recombineering, in vivo genetic engineering using the bacteriophage λ Red generalized recombination system, was used to create various modifications of a multicopy plasmid derived from pBR322. All genetic modifications possible on the E. coli chromosome and on bacterial artificial chromosomes (BACs) are also possible on multicopy plasmids and are obtained with similar frequencies to their chromosomal counterparts, including creation of point mutations (5-10% unselected frequency), deletions and substitutions. Parental and recombinant plasmids are nearly always present as a mixture following recombination, and circular multimeric plasmid molecules are often generated during the recombineering.

‣ Genetic Analysis of Zinc-Finger Nuclease-Induced Gene Targeting in Drosophila

Bozas, Ana; Beumer, Kelly J.; Trautman, Jonathan K.; Carroll, Dana
Fonte: Genetics Society of America Publicador: Genetics Society of America
Tipo: Artigo de Revista Científica
Publicado em /07/2009 Português
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Using zinc-finger nucleases (ZFNs) to cleave the chromosomal target, we have achieved high frequencies of gene targeting in the Drosophila germline. Both local mutagenesis through nonhomologous end joining (NHEJ) and gene replacement via homologous recombination (HR) are stimulated by target cleavage. In this study we investigated the mechanisms that underlie these processes, using materials for the rosy (ry) locus. The frequency of HR dropped significantly in flies homozygous for mutations in spnA (Rad51) or okr (Rad54), two components of the invasion-mediated synthesis-dependent strand annealing (SDSA) pathway. When single-strand annealing (SSA) was also blocked by the use of a circular donor DNA, HR was completely abolished. This indicates that the majority of HR proceeds via SDSA, with a minority mediated by SSA. In flies deficient in lig4 (DNA ligase IV), a component of the major NHEJ pathway, the proportion of HR products rose significantly. This indicates that most NHEJ products are produced in a lig4-dependent process. When both spnA and lig4 were mutated and a circular donor was provided, the frequency of ry mutations was still high and no HR products were recovered. The local mutations produced in these circumstances must have arisen through an alternative...

‣ Single-stranded DNA binding protein from human malarial parasite Plasmodium falciparum is encoded in the nucleus and targeted to the apicoplast

Prusty, Dhaneswar; Dar, Ashraf; Priya, Rashmi; Sharma, Atul; Dana, Srikanta; Choudhury, Nirupam Roy; Rao, N. Subba; Dhar, Suman Kumar
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Português
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Apicoplast, an essential organelle of human malaria parasite Plasmodium falciparum contains a ∼35 kb circular genome and is a possible target for therapy. Proteins required for the replication and maintenance of the apicoplast DNA are not clearly known. Here we report the presence of single–stranded DNA binding protein (SSB) in P falciparum. PfSSB is targeted to the apicoplast and it binds to apicoplast DNA. A strong ssDNA binding activity specific to SSB was also detected in P. falciparum lysate. Both the recombinant and endogenous proteins form tetramers and the homology modelling shows the presence of an oligosaccharide/oligonucleotide-binding fold responsible for ssDNA binding. Additionally, we used SSB as a tool to track the mechanism of delayed death phenomena shown by apicoplast targeted drugs ciprofloxacin and tetracycline. We find that the transport of PfSSB is severely affected during the second life cycle following drug treatment. Moreover, the translation of PfSSB protein and not the transcription of PfSSB seem to be down-regulated specifically during second life cycle although there is no considerable change in protein expression profile between drug-treated and untreated parasites. These results suggest dual control of translocation and translation of apicoplast targeted proteins behind the delayed death phenomena.

‣ Structural and Sequence Analysis of Imelysin-Like Proteins Implicated in Bacterial Iron Uptake

Xu, Qingping; Rawlings, Neil D.; Farr, Carol L.; Chiu, Hsiu-Ju; Grant, Joanna C.; Jaroszewski, Lukasz; Klock, Heath E.; Knuth, Mark W.; Miller, Mitchell D.; Weekes, Dana; Elsliger, Marc-André; Deacon, Ashley M.; Godzik, Adam; Lesley, Scott A.; Wilson, Ia
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 25/07/2011 Português
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Imelysin-like proteins define a superfamily of bacterial proteins that are likely involved in iron uptake. Members of this superfamily were previously thought to be peptidases and were included in the MEROPS family M75. We determined the first crystal structures of two remotely related, imelysin-like proteins. The Psychrobacter arcticus structure was determined at 2.15 Å resolution and contains the canonical imelysin fold, while higher resolution structures from the gut bacteria Bacteroides ovatus, in two crystal forms (at 1.25 Å and 1.44 Å resolution), have a circularly permuted topology. Both structures are highly similar to each other despite low sequence similarity and circular permutation. The all-helical structure can be divided into two similar four-helix bundle domains. The overall structure and the GxHxxE motif region differ from known HxxE metallopeptidases, suggesting that imelysin-like proteins are not peptidases. A putative functional site is located at the domain interface. We have now organized the known homologous proteins into a superfamily, which can be separated into four families. These families share a similar functional site, but each has family-specific structural and sequence features. These results indicate that imelysin-like proteins have evolved from a common ancestor...

‣ 2-(2-Hydroxy-5-nitrobenzylidene)-1,3-indanedione versus Fluorescein Isothiocyanate in Interaction with Anti-hFABP Immunoglobulin G1: Fluorescence Quenching, Secondary Structure Alteration and Binding Sites Localization

Stan, Dana; Mihailescu, Carmen-Marinela; Savin, Mihaela; Matei, Iulia
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 31/01/2013 Português
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The first step in determining whether a fluorescent dye can be used for antibody labeling consists in collecting data on its physical interaction with the latter. In the present study, the interaction between the 2-(2-hydroxy-5-nitrobenzylidene)-1,3-indanedione (HNBID) dye and the IgG1 monoclonal mouse antibody anti-human heart fatty acid binding protein (anti-hFABP) has been investigated by fluorescence and circular dichroism spectroscopies and complementary structural results were obtained by molecular modeling. We have determined the parameters characterizing this interaction, namely the quenching and binding constants, classes of binding sites, and excited state lifetimes, and we have predicted the localization of HNBID within the Fc region of anti-hFABP. The key glycosidic and amino acid residues in anti-hFABP interacting with HNBID have also been identified. A similar systematic study was undertaken for the well-known fluorescein isothiocyanate fluorophore, for comparison purposes. Our results recommend HNBID as a valuable alternative to fluorescein isothiocyanate for use as a fluorescent probe for IgG1 antibodies.

‣ The Green Bank Telescope HII Region Discovery Survey: III. Kinematic Distances

Anderson, L. D.; Bania, T. M.; Balser, Dana S.; Rood, Robert T.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 18/05/2012 Português
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Using the HI Emission/Absorption method, we resolve the kinematic distance ambiguity and derive distances for 149 of 182 (82%) HII regions discovered by the Green Bank Telescope HII Region Discovery Survey (GBT HRDS). The HRDS is an X-band (9GHz, 3cm) GBT survey of 448 previously unknown HII regions in radio recombination line and radio continuum emission. Here we focus on HRDS sources from 67deg. > l > 18deg., where kinematic distances are more reliable. The 25 HRDS sources in this zone that have negative recombination line velocities are unambiguously beyond the orbit of the Sun, up to 20kpc distant. They are the most distant HII regions yet discovered. We find that 61% of HRDS sources are located at the far distance, 31% at the tangent point distance, and only 7% at the near distance. "Bubble" HII regions are not preferentially at the near distance (as was assumed previously) but average 10kpc from the Sun. The HRDS nebulae, when combined with a large sample of HII regions with previously known distances, show evidence of spiral structure in two circular arc segments of mean Galactocentric radii of 4.25 and 6.0kpc. We perform a thorough uncertainty analysis to analyze the effect of using different rotation curves, streaming motions...

‣ The Compton Microscope: Using the Energy Dependence of QPO Amplitudes to Probe Their Origin in Accretion Disks

Lehr, Dana E.; Wagoner, Robert V.; Wilms, Joern
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/04/2000 Português
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We report the development of a new tool to determine the origin of quasi-periodic oscillations (QPOs) in accretion disk systems. The technique uses the source energy spectrum and the energy dependence of the QPO fractional amplitude to restrict the location of the emission region of the modulated photons, which are assumed to originate in the inner accretion disk. Both Monte Carlo and semi-analytical methods are presented. We assume the accretion disk is enshrouded by a slab atmosphere of hot electrons in which unsaturated Compton scattering produces the high-energy spectrum. Properties of the atmosphere, in particular the electron temperature, are assumed functions of radius from the central compact object. We show that our model reproduces the observed energy dependence of the fractional amplitude of the 67 Hz QPO in GRS 1915+105 if the QPO is assumed to originate within five gravitational radii from the innermost stable circular orbit.; Comment: 4 pages, 2 figures, submitted to The Astrophysical Journal, Letters, on February 11, 2000, uses emulateapj LaTeX style file